I was wondering, are there any known genetic limitations that would NOT allow for: a) the creation of new traits in organisms (which would lead to) evolution between kinds.

As a springboard; it would seem to me that sign epistasis would potentially limit mutation of alleles with large epistatic loads. This would restrict mutations that would cause drastic new traits to arise that would be positive enough to select for. This would restrict organisms to primarily mutate alleles with less epistatic load, which would cause slower development of new traits, which would disappear due to further mutation before becoming complex new systems or traits (I am thinking of musculoskeletal systems here, or blood's ability to clot, fight infections, etc). I admit my understanding of sign epistasis is a bit fuzzy.

If we find empirical data for such limitations, it would be one of the biggest stumbling blocks to evolution since abiogenesis. I am just wondering if such limitations have been observed. I have not been able to find an article on this that I could make sense of.

I was wondering, are there any known genetic limitations that would NOT allow for: a) the creation of new traits in organisms (which would lead to) evolution between kinds.

As a springboard; it would seem to me that sign epistasis would potentially limit mutation of alleles with large epistatic loads. This would restrict mutations that would cause drastic new traits to arise that would be positive enough to select for. This would restrict organisms to primarily mutate alleles with less epistatic load, which would cause slower development of new traits, which would disappear due to further mutation before becoming complex new systems or traits (I am thinking of musculoskeletal systems here, or blood's ability to clot, fight infections, etc). I admit my understanding of sign epistasis is a bit fuzzy.

If we find empirical data for such limitations, it would be one of the biggest stumbling blocks to evolution since abiogenesis. I am just wondering if such limitations have been observed. I have not been able to find an article on this that I could make sense of.

Hmmmm, it seems to me that the biggest stumbling blocks to both macroevolution and abiogenesis, is the fact that there are no empirical facts to support either. Therefore, looking for something nonexistent, to support two more things that are nonexistent, is basically speculating on speculation.

To clarify, I am not asking about abiogenesis because I have read an article from http://www.amazon.co...n/dp/0890513414 on how many barriers there are to it based on observations from chemistry.

I guess I am saying, I do not know how DNA leads to cell differentiation, or how DNA contributes to the formation of complex structures such as the wings of a bird, and I was wondering if there was a scientific limitation for DNA to change through mutation to allow for new structures, in steps or otherwise. To keep things simple I will limit my inquiry to the example of developing a single photosensitive cell in a multicellular organism by random mutation, such as the one that evolutionists claim was the beginning of an eye. I have a clear idea of my question without knowing if it is even a reasonable question. I feel quite naive, yet remain curious. Any information you could provide would be helpful.

...To keep things simple I will limit my inquiry to the example of developing a single photosensitive cell in a multicellular organism by random mutation, such as the one that evolutionists claim was the beginning of an eye. I have a clear idea of my question without knowing if it is even a reasonable question. I feel quite naive, yet remain curious. Any information you could provide would be helpful.

To try to answer your question, as well, I would say the blueprint itself is a barrier to genetic variation, a JellyFish has the physical genome for a Jellyfish (current species/[kind]) and not a tree... function and purpose... If you look at the same evidence from the evolutionary presupposition you will find the missing links that aren't missing (which is what Ron was discussing/explaining) Another helpful thing to note is models are different than reality..., I'm glad they're talking about epistasis and not the punnett square model...edit: the video I put up didn't cover the topic specifically.

To try to answer your question, as well, I would say the blueprint itself is a barrier to genetic variation, a JellyFish has the physical genome for a Jellyfish (current species/[kind]) and not a tree... function and purpose... If you look at the same evidence from the evolutionary presupposition you will find the missing links that aren't missing (which is what Ron was discussing/explaining) Another helpful thing to note is models are different than reality..., I'm glad they're talking about epistasis and not the punnett square model...edit: the video I put up didn't cover the topic specifically.

I was thinking about this again today. I think you are on to something. It is not quite scientific empirical barriers like I am hoping for, but it is sound reasoning. The main problem with plausibility is that evolutionists wriggle out of it with other plausibility arguments. I was talking with one who said that "evolution has nothing to do with abiogenesis and makes no claims to origins of life, it just explains the diversity of species on earth today". Since abiogenesis is chemically impossible, it makes sense that they would try to distance themselves from this, but it does have implications on origins.

If abiogenesis is out of the question, then life has to come from God. It does not make sense to have a God who has at least enough knowledge and power to create the universe and the laws that run it, to allow for the laws to be able to sustain life, yet plays around with life through evolution to slowly tweak it into different species, almost like an indecisive/ignorant child. If God is creator of the heavens and the earth, then what is to stop Him from creating human beings out of the dust of the earth instantaneously? What is to stop Him from creating a diversity of life, and a planet to create a self sustaining ecosystem that is very intricately interdependent? It would seem that DNA has enough diversity to allow animals to adapt to their environment, but the core organism stays relatively the same. That any given random mutation would break functionality of an organism as a whole before complexity was added in any real way. This is what scientific data suggests, but evolutionists and atheists keep hoping for the salvation of a "missing link". Without the hope of a missing link, they would be forced to consider the implications of God's authority over them. It never ceases to amaze me that God saved me from agnosticism.

I was thinking about this again today. I think you are on to something.

He didn't quite answer your question though, did he ? You asked about a barrier to keep a multicellular organism from evolving a light-sensitive cell, and he answered about jellyfish remaining jellyfish. Looks to me like there's a big difference between the two.Note also that in cladistics it's impossible for a jellyfish to evolve into a non-jellyfish - not because of barriers to evolution, but because all evolution comes in addition to what came before. Even if we picture a jellyfish that lost all its jellyfishy characteristics that made it hard to recognize as belonging to the jellyfish group, we'd still end up classifying it there on molecular evidence.It's like tetrapods - while songbirds are very different from frogs and both are very different from Tiktaalik, they all still belong to the group Tetrapoda, and they share the characteristic features of that group. Once upon a time Tetrapoda might have included just leggy fish, and now it includes songbirds and frogs, but those songbirds and frogs still have the skeletal, physiological and molecular structures that make them tetrapods. Even when they lose some of those features - like snakes or dolphins - all their other features make it clear they're still firmly nested within that group.

It is not quite scientific empirical barriers like I am hoping for, but it is sound reasoning. The main problem with plausibility is that evolutionists wriggle out of it with other plausibility arguments. I was talking with one who said that "evolution has nothing to do with abiogenesis and makes no claims to origins of life, it just explains the diversity of species on earth today". Since abiogenesis is chemically impossible, it makes sense that they would try to distance themselves from this, but it does have implications on origins.

We don't know that abiogenesis is chemically impossible. We have no clue how it happened, or what it even consisted of, but we don't know that it's impossible. We don't even know how improbable it would be on the primordial Earth - that would require knowing what the conditions were on primordial Earth, and although we know more than we used to we still don't know much.

It would seem that DNA has enough diversity to allow animals to adapt to their environment, but the core organism stays relatively the same.

What core is that ? I mean, is there a level of classification you can point to and say "animals within a group under this level share a core similarity with each other but are completely unlike the members of other groups" ?

That any given random mutation would break functionality of an organism as a whole before complexity was added in any real way.

That's why complexity gets added gradually...

This is what scientific data suggests, but evolutionists and atheists keep hoping for the salvation of a "missing link". Without the hope of a missing link, they would be forced to consider the implications of God's authority over them. It never ceases to amaze me that God saved me from agnosticism.

The "missing link" can't even be called a hoary old chestnut anymore, it's so old. Do you even know what "missing link" you're talking about, i.e. between what and what ? Originally the term was used to refer to the lack of transitional fossils between humans and non-human apes. Then they discovered Australopithecus, and suddenly there were two missing links : between non-human apes and Australopithecus, and between Australopithecus and humans. Then they discovered Homo Erectus, and there were six missing links ! You can see where this is going. And it did continue going : we have enough fossils now to have a pretty fine-grained picture of the transition between non-human apes and humans.Finding a "missing link" (i.e. a transitional fossil for a stage that hadn't been observed previously) is always fascinating because it improves scientists' understanding of evolutionary history, and sometimes when said history isn't known it can blow a case wide open (although with molecular phylogenies I'd say that happens less now), but there is no "missing link" that the whole theory of evolution hinges on.

Of course there is one scientific question that is very much wide open and could do with the appearance of a conveniently transitional form, and which is relevant to what you're saying, and that's the question of how life arose in the first place. But that's not something that would fossilize so nobody is hoping for a "missing link" to show up in that context.

To clarify, I am not asking about abiogenesis because I have read an article from http://www.amazon.co...n/dp/0890513414 on how many barriers there are to it based on observations from chemistry.

I guess I am saying, I do not know how DNA leads to cell differentiation, or how DNA contributes to the formation of complex structures such as the wings of a bird, and I was wondering if there was a scientific limitation for DNA to change through mutation to allow for new structures, in steps or otherwise. To keep things simple I will limit my inquiry to the example of developing a single photosensitive cell in a multicellular organism by random mutation, such as the one that evolutionists claim was the beginning of an eye. I have a clear idea of my question without knowing if it is even a reasonable question. I feel quite naive, yet remain curious. Any information you could provide would be helpful.

There are mathematical calculations that have been made, which limit the possibility of mutations to accomplish such a task and it was made by an evolutionists who stacked the deck in favor of evolution.

What core is that ? I mean, is there a level of classification you can point to and say "animals within a group under this level share a core similarity with each other but are completely unlike the members of other groups" ?

Try the science of taxonomy. It's a science because it's an empirical fact that all species fit into their own genus and no new genotype has ever been created by any process other than hybridization.

He didn't quite answer your question though, did he ? You asked about a barrier to keep a multicellular organism from evolving a light-sensitive cell, and he answered about jellyfish remaining jellyfish. Looks to me like there's a big difference between the two.Note also that in cladistics it's impossible for a jellyfish to evolve into a non-jellyfish - not because of barriers to evolution, but because all evolution comes in addition to what came before. Even if we picture a jellyfish that lost all its jellyfishy characteristics that made it hard to recognize as belonging to the jellyfish group, we'd still end up classifying it there on molecular evidence.It's like tetrapods - while songbirds are very different from frogs and both are very different from Tiktaalik, they all still belong to the group Tetrapoda, and they share the characteristic features of that group. Once upon a time Tetrapoda might have included just leggy fish, and now it includes songbirds and frogs, but those songbirds and frogs still have the skeletal, physiological and molecular structures that make them tetrapods. Even when they lose some of those features - like snakes or dolphins - all their other features make it clear they're still firmly nested within that group.

We don't know that abiogenesis is chemically impossible. We have no clue how it happened, or what it even consisted of, but we don't know that it's impossible. We don't even know how improbable it would be on the primordial Earth - that would require knowing what the conditions were on primordial Earth, and although we know more than we used to we still don't know much.

What core is that ? I mean, is there a level of classification you can point to and say "animals within a group under this level share a core similarity with each other but are completely unlike the members of other groups" ?

That's why complexity gets added gradually...

The "missing link" can't even be called a hoary old chestnut anymore, it's so old. Do you even know what "missing link" you're talking about, i.e. between what and what ? Originally the term was used to refer to the lack of transitional fossils between humans and non-human apes. Then they discovered Australopithecus, and suddenly there were two missing links : between non-human apes and Australopithecus, and between Australopithecus and humans. Then they discovered Homo Erectus, and there were six missing links ! You can see where this is going. And it did continue going : we have enough fossils now to have a pretty fine-grained picture of the transition between non-human apes and humans.Finding a "missing link" (i.e. a transitional fossil for a stage that hadn't been observed previously) is always fascinating because it improves scientists' understanding of evolutionary history, and sometimes when said history isn't known it can blow a case wide open (although with molecular phylogenies I'd say that happens less now), but there is no "missing link" that the whole theory of evolution hinges on.

Of course there is one scientific question that is very much wide open and could do with the appearance of a conveniently transitional form, and which is relevant to what you're saying, and that's the question of how life arose in the first place. But that's not something that would fossilize so nobody is hoping for a "missing link" to show up in that context.

No he did not answer my question as I stated in my reply. The majority of what I posted in that last post boils down to this: if we cannot explain the origin of life through abiogenesis, and God has created life on earth, then theistic evolution does not make sense. Moving on to other points you made:

Here are some of the chemical barriers to abiogenesis:

1) In the absence of enzymes, there is no chemical reaction that produces the sugar ribose, the "backbone" of RNA and DNA.2) Enzymes cannot be synthesized in the absence of RNA and ribosomes. (when combined with 1 this creates a catch 22)3) Chemical reactions in prebiotic soups produce other sugars that prevent RNA and DNA replication. (Further complicates 2 and therefore 1 also)4) The most common abiogenesis theories claim that life arose at hydrothermal vents in the ocean. However, recent studies show that polymerization of the molecules necessary for cell membrane assembly cannot occur in salt water. Other studies show that the early oceans were at least twice as salty as they are now.Link.

Time is no savior if the chemistry can't happen under any circumstances. Although you can still argue that time and scientific research will eventually lead to discovery of the "right circumstances" so then time is the savior once again.

Australopithecus is a bad example of transition between apes and man, they are apes, nothing more, nothing less:

2. Even if Australopithecines were fully bipedal, that would not make them any less apes. [...] Furthermore, it needs to be noted that modern apes do sometimes walk upright in a manner called facultative bipedalism.

That said, there is evidence suggesting that australopithecines were knuckle-walking apes. A 1994 study [1] showed that the australopithecine inner ear was consistent with that of facultative bipedalism, knuckle-walking, and arboreal climbing of apes. It also contrasted them to the obligatory bipedalism of the humans called Homo erectus. More recent evidence shows that australopithecine wrist anatomy was that of a knuckle-walking ape. [2]

3. Australopithecus afarensis clearly had ape-like teeth including well-defined canines [3]. The adult Australopithecus africanus seems to have lost the well-defined canines and gained more human-like teeth [4], yet The Taung Child shows that their children had more ape-like teeth with well-defined canines [5]. The most likely cause of the difference is that in the adults the canine and other teeth have been worn by diet making them look more human than they really are.

Neanderthals are another bad example commonly offered; they are human beings whose genetic "uniqueness" exists in modern day European populations.

Is this gradual increase of complexity observable or are you talking about organisms taking advantage of genetic diversity and mutations that cause minor changes to existing features (such as size or coloring) that help organisms to adapt to environmental pressures?

Try the science of taxonomy. It's a science because it's an empirical fact that all species fit into their own genus and no new genotype has ever been created by any process other than hybridization.

Actually, the empirical fact about taxonomy is that all divisions above that of species are fairly arbitrary and correspond to how much homogeneity and how much variability humans "feel" a group contains, which leads to the genera of less-familiar groups containing the same amount of genetic or morphological diversity as whole families of charismatic megafauna, and this effect being more and more pronounced as the organisms in question are more and more similar/familiar to humans, until you get to humans themselves who are put in their own genus even though any other two species who were as similar as we are to chimpanzees would share a genus.For example, compare the genus Felis (cats) to the genus Camponotus (carpenter ants) :http://en.wikipedia.org/wiki/Felishttp://en.wikipedia....wiki/Camponotus

The Felis genus contains 6 species : the jungle cat, the sand cat, the black-footed cat, the wildcat, the domestic cat, the chinese mountain cat, and Martelli's cat (which we apparently only have fossils of). They mostly differ in size (14 to 37 inches), in coloring, geographical range (only Africa and Eurasia though, except of course for domestic cats) and some lifestyle aspects (how much they climb, how solitary they are...). Aside from size, 99% of the morphological variation in the genus happens within one species : domestic cats. And that's through human selective breeding.

The Camponotus genus contains over 1000 species so I'm not going to list them, but just looking at a few of the "selected species" on the Wikipedia page I have : Camponotus saundersi, whose workers can explode (an ability shared by a few other asian species in the genus), Camponotus Gigas or "giant forest ant", one of the largest ants at around an inch long, Camponotus nearticus, one of the smaller carpenter ants at around 2mm long, Camponotus consobrinus or "sugar ant", who farm aphids (like some but not all other species of this genus), Camponotus festinatus who can only feed on liquids, Camponotus schmitzi who live in a mutualistic relationship with a carnivorous plant, Camponotus anderseni who have the ability to switch to anaerobic respiration (they live in mangroves, when there's a flood they block the entrance to the nest but the oxygen soon runs out)... They're also found all over the world including both Americas and Australia.

Wait, did I say a genus of unfamiliar animals had as much variability as a family of charismatic megafauna ? That kind of variability could almost cover an order ! And that's with famous insects. It gets even crazier with plants, or nematodes. Let alone bacteria. (By the way, I like how the Wiki page for Camponotus begins its section about exploding ants : "In at least nine Southeast Asian species of the Cylindricus complex"... If only, if only there were a word they could use to designate a grouping larger than "species" but still containing animals that have almost everything in common !)

The Felis genus contains 6 species : the jungle cat, the sand cat, the black-footed cat, the wildcat, the domestic cat, the chinese mountain cat, and Martelli's cat (which we apparently only have fossils of). They mostly differ in size (14 to 37 inches), in coloring, geographical range (only Africa and Eurasia though, except of course for domestic cats) and some lifestyle aspects (how much they climb, how solitary they are...). Aside from size, 99% of the morphological variation in the genus happens within one species : domestic cats. And that's through human selective breeding.

Those species also have a completely different genome from one another, which is why they are different species that share enough morphological similarities to be placed within the same genus. Variation within a species did not lead to domestic cats becoming a new species, so tap dancing around the fact that taxonomy is empirical does not make it arbitrary. Most people know that the Egyptians domesticated the African wild cat, which is the ancestor of most domestic breeds today. A DNA comparison will still render a solid confirmation that they share the same genotype as with most domesticated dogs and wolves.

Evolution depends upon butchering the science of taxonomy so they can create an illusion of finely graduated morphologies between higher taxonomic ranks, but they can't even provide any empirical evidence of genetic speciation within a genus.

Those species also have a completely different genome from one another, which is why they are different species that share enough morphological similarities to be placed within the same genus. Variation within a species did not lead to domestic cats becoming a new species, so tap dancing around the fact that taxonomy is empirical does not make it arbitrary. Most people know that the Egyptians domesticated the African wild cat, which is the ancestor of most domestic breeds today. A DNA comparison will still render a solid confirmation that they share the same genotype as with most domesticated dogs and wolves.

Evolution depends upon butchering the science of taxonomy so they can create an illusion of finely graduated morphologies between higher taxonomic ranks, but they can't even provide any empirical evidence of genetic speciation within a genus.

... I don't really see what that has to do with what we were discussing. The criteria for defining species (which isn't "completely different genome" by the way; except for perfect clones all genomes are different. And every degree of difference between two genomes exist in nature, and there isn't one specific degree of difference that corresponds to species) has nothing to do with the criteria for defining genera. Species, unlike the higher taxonomic levels, isn't an arbitrary concept. It's fuzzy in many cases but not arbitrary. But you haven't addressed my contention that genera are an arbitrary concept.

As for empirical evidence of "genetic speciation" within a genus, what does "genetic speciation" mean ? Is it different from ordinary speciation ?

... I don't really see what that has to do with what we were discussing. The criteria for defining species (which isn't "completely different genome" by the way; except for perfect clones all genomes are different. And every degree of difference between two genomes exist in nature, and there isn't one specific degree of difference that corresponds to species) has nothing to do with the criteria for defining genera. Species, unlike the higher taxonomic levels, isn't an arbitrary concept. It's fuzzy in many cases but not arbitrary. But you haven't addressed my contention that genera are an arbitrary concept.

As for empirical evidence of "genetic speciation" within a genus, what does "genetic speciation" mean ? Is it different from ordinary speciation ?

Are you now in denial that the science of DNA profiling exists as well? Not only can we positively identify an exact species by it's DNA, but we can also identify a specific individual by it's DNA.

So, if you don't know what genetic speciation means, then it's because you don't employ any empirical measure to ToE. If genera were an arbitrary concept, then the genome of each species in it could freely interbreed.

Are you now in denial that the science of DNA profiling exists as well? Not only can we positively identify an exact species by it's DNA, but we can also identify a specific individual by it's DNA.

Indeed. Because individuals have different DNA ! So do different species, as well as different genera and all classification levels above. But there is no amount of DNA differences that distinguishes species, let alone the higher levels. Some species have lots of genetic diversity, and some different species are very similar genetically. What makes species an important, non-arbitrary classification level (and does imply genetic differences, although they don't define it, in animals at least) is that it's defined by a lack of gene flow between populations. If all individuals interbreed normally, they're a single species. If they can't possibly interbreed, they're in different species. There's a huge amounts of fuzziness at the margins, with those populations that don't usually interbreed in the wild but are still perfectly able to do so, those populations who can interbreed but with lowered reproductive success, etc. And that's among animals : plants have much weaker barriers to inter-species reproduction to the point some individuals can successfully hybridize even with other genera. But plants are weird like that.

So, if you don't know what genetic speciation means, then it's because you don't employ any empirical measure to ToE. If genera were an arbitrary concept, then the genome of each species in it could freely interbreed.

Um, no. If species were an arbitrary concept... well, even that wouldn't tell us whether the genome of each individual in it could interbreed because the concept would have nothing to do with interbreeding. Because "arbitrary".Of course species aren't an arbitrary concept, they're defined by the lack of interbreeding between individuals, so by the definition of "species" individuals of different species can't interbreed. Except for the fuzzy cases, in which case it's "individuals of different species are unlikely to interbreed successfully".That has nothing to do with genera, which are a classification level above that of species. They aren't even an absolute barrier to interbreeding anymore than species are. Plants aside, obviously cross-genus hybrids are much rarer and less likely to be fertile than cross-species hybrids but some still exist : take the servical/caraval, the wholphin, the zubron... Apparently there's even been a fertile sheep-goat hybrid.

Indeed. Because individuals have different DNA ! So do different species, as well as different genera and all classification levels above. But there is no amount of DNA differences that distinguishes species, let alone the higher levels.

It isn't the differences that science uses to make a species determination, it's the similarities, which are marked between different species.

Some species have lots of genetic diversity, and some different species are very similar genetically.

The variation within a specie is produced by Pleiotropy, which is the selection of a specific trait that influences the other genes within that group. Other species are different genetically - wasn't that the point to start with?

Um, no. If species were an arbitrary concept... well, even that wouldn't tell us whether the genome of each individual in it could interbreed because the concept would have nothing to do with interbreeding. Because "arbitrary".Of course species aren't an arbitrary concept, they're defined by the lack of interbreeding between individuals, so by the definition of "species" individuals of different species can't interbreed. Except for the fuzzy cases, in which case it's "individuals of different species are unlikely to interbreed successfully".That has nothing to do with genera, which are a classification level above that of species. They aren't even an absolute barrier to interbreeding anymore than species are. Plants aside, obviously cross-genus hybrids are much rarer and less likely to be fertile than cross-species hybrids but some still exist : take the servical/caraval, the wholphin, the zubron... Apparently there's even been a fertile sheep-goat hybrid.

Yes. That makes the claim that fertility is a valid definition of a specie mute. Genetic speciation has to occur to account for the different genomes within each individual species of each genera and there is no example of the creation of a new species "genetically" at the genus level except through hybridization, which still makes taxonomy an empirical fact and not arbitrary.

It isn't the differences that science uses to make a species determination, it's the similarities, which are marked between different species.

The similarities are even more marked between different individuals, or different subspecies so I don't see the link here. Maybe you should think of looking up "Biological Species Concept" one of these days.

The variation within a specie is produced by Pleiotropy, which is the selection of a specific trait that influences the other genes within that group. Other species are different genetically - wasn't that the point to start with?

Species are different genetically. Individuals are different genetically. Genera are different genetically. Different cells within a same multicellular organism are often different genetically if it comes to that. The point is that "different genetically" isn't what defines taxonomical levels. It's an important feature but not the defining one AFAIK.

Yes. That makes the claim that fertility is a valid definition of a specie mute.

Amusing. You think that the existence of fuzzy borders in the "do they interbreed ?" criteria makes the definition moot ? Then how come you're proposing "genetic differences", which is even fuzzier in that it's an actual continuum ? There's apparently 0.2% difference in the dog and wolf genomes, and a 4% difference between the wolf and coyote genomes. What % difference defines a species, exactly ? And a genus ?

Genetic speciation has to occur to account for the different genomes within each individual species of each genera and there is no example of the creation of a new species "genetically" at the genus level except through hybridization, which still makes taxonomy an empirical fact and not arbitrary.

What does "the creation of a new species at the genus level" mean ? Don't you mean the creation of a new genus ? That's impossible in the current cladistics-oriented way of classifying animals simply because a clade is defined as all the descendants of a certain common ancestor - so however much those descendants diverge they remain that common ancestor's descendants. Anyway, here are a few quotes from the Wikipedia page for "genus" :"The composition of a genus is determined by a taxonomist. The standards for genus classification are not strictly codified, and hence different authorities often produce different classifications for genera."

"There are no hard and fast rules that a taxonomist has to follow in deciding what does and what does not belong in a particular genus. This does not mean that there is no common ground among taxonomists in what constitutes a "good" genus. For instance, some rules-of-thumb for delimiting a genus are outlined in Gill. According to these, a genus should fulfill three criteria to be descriptively useful:

1.monophyly Ã¢â‚¬â€œ all descendants of an ancestral taxon are grouped together;2.reasonable compactness Ã¢â‚¬â€œ a genus should not be expanded needlessly; and3.distinctness Ã¢â‚¬â€œ in regards of evolutionarily relevant criteria, i.e. ecology, morphology, or biogeography; note that DNA sequences are a consequence rather than a condition of diverging evolutionary lineages except in cases where they directly inhibit gene flow (e.g. postzygotic barriers).

But Wikipedia is Wikipedia, so I'm sure you have better sources showing that genera are a hard-and-fast well-defined taxonomic level that is defined through genetic differences and/or lack of interbreeding ?

The similarities are even more marked between different individuals, or different subspecies so I don't see the link here.

Then you confirm that you do see the link in your very next statement below:

There's apparently 0.2% difference in the dog and wolf genomes, and a 4% difference between the wolf and coyote genomes.

I find it hard to believe that you can't understand the math that empirically establishes the fact that 0.02% difference in a species is much less than 4% difference in a completely different species. That's 20 orders of magnitude difference.

What % difference defines a species, exactly ? And a genus ?

It isn't the amount of differences as I've said more than once now. It's the type of differences. The wolf and coyote have totally different gene groups and arrangements, while the species only shares minute mutations of the same gene groups and arrangments.

If I had two identical pairs of shoes and one pair had a small tear in it, could it be arbitrarily a boot now? I think that anyone could see that the boot is constructed differently so that it can't be considered a shoe and that the minor variation in the shoe still renders it a shoe.

Or consider this: My father is up to .1% different from me. Does that make me a .1% different species? No. It means that during recombination, not only were some of his genes replaced by my mothers, but I may have underwent some insertions or deletions that make it impossible to be his perfect clone.

I find it hard to believe that you can't understand the math that empirically establishes the fact that 0.02% difference in a species is much less than 4% difference in a completely different species. That's 20 orders of magnitude difference.

You've got one 0 too many there. And you seem to have missed the bit where my whole point is that there's a difference in both cases - and you haven't told me yet where the cutoff point is. If the definition was all about "genome differences" there should either be no difference in one case, OR there should be a specific cutoff point. So yeah, 0.2% is a lot less than 4% - but they're both genomic difference so that means instead of "genomic difference" defining species it should be a certain amount of genomic difference. What is that amount ? 0.5% ? 1% ? 2% ? 3% ?And how about the cutoff point for a genus ? After all, 4% is also about the difference between humans and chimpanzee, yet the wolf and coyote are in the same genus while humans and chimpanzees aren't.

It isn't the amount of differences as I've said more than once now. It's the type of differences. The wolf and coyote have totally different gene groups and arrangements, while the species only shares minute mutations of the same gene groups and arrangments.

Interesting, I hadn't seen you say that before sorry. But again, obviously there are differences, whether by % or in "groups" or "arrangements". Those can only be used to define taxonomic classes if we know which differences exactly define a species, and a genus, and higher classes. So what gene groups and arrangements are you thinking of exactly here ?

Interesting line of thought there. I guess we have to wait for the gurus to give us their take on that one. If i were to propose a conspiracy theory (based on the assumption that that question HAS been asked before) i would say no-one would want to answer a question that would put an end to a theory held in such high esteem.